Evaluations of primary metals from NHEXAS Arizona: distributions and preliminary exposures. National Human Exposure Assessment Survey.

NHEXAS AZ is a multimedia, multipathway exposure assessment survey designed to evaluate metals and other analytes. This paper reports the analyte-specific concentration distributions in each of the media examined (air, soil, house dust, food, beverage, and water), for various methodologies used (inductively coupled plasma-atomic emission spectroscopy and hydride generation-atomic absorption spectroscopy). Results are reported for the five primary metals (Pb, As, Cd, Cr, and Ni). Ingestion was the most important pathway of exposure. Metal concentrations in air were very low (ng/m3) and found only above the 90th percentile. Metals were commonly found in house dust and soil. Exposure transfer coefficients minimize the importance of this component for those over the age of 6 years. When ranked by exposure, food, beverage, and water appeared to be the primary contributors of metal exposure in NHEXAS AZ. For instance, at the 90th percentile, Pb was undetected in air, found at 131 and 118 microg/m3 in floor dust and soil, respectively, and measured at 16 microg/kg in food, 7.1 microg/kg in beverage, and 2.0 and 1.3 microg/l in drinking and tap water, respectively. We calculated preliminary estimates of total exposure (microg/day) for each participant and examined them independently by age, gender, and ethnicity as reported by the subjects in the NHEXAS questionnaire. At the 90th percentile for Pb, total exposures were 64 microg/day across all subjects (n=176); adult men (n=55) had the greatest exposure (73 microg/day) and children (n=35) the least (37 microg/day). Hispanics (n=54) had greater exposure to Pb (68 microg/day) than non-Hispanics (n=119; 50 microg/day), whereas non-Hispanics had greater exposure for all other metals reported. These results have implications related to environmental justice. The NHEXAS project provides information to make informed decisions for protecting and promoting appropriate public health policy.

Computed tomography of acoustic neuroma.

Review of computed tomographic (CT) scans of 49 consecutive patients with surgically excised acoustic neuromas revealed positive scans in 80% following contrast enhancement, with 20% false negative scans. All tumors over 2 cm in diameter were shown by optimal scans with contrast enhancement. The positive scans were evaluated to determine the accuracy of the size of the lesions as predicted by the scan. A radiological approach to the evaluation of suspected acoustic neuromas is suggested.

Relationships between hearing loss and cognition in normally hearing aged persons.

The relationships between mild hearing losses and cognitive functioning were studied for two independently selected samples of aged subjects whose hearing was within normal limits. One group had 47 males of mean age 71.5 (SD 4.8) who were selected for their excellent health status. The second group consisted of 38 females of mean age 75.9 (SD 5.3), all of whom had some significant physical pathology. Hearing losses at various frequency levels (from 125 to 8000 cps) were correlated with performance on cognitive tests such as the WAIS, with age effects then being partialled out. The results reveal substantial associations between hearing losses and scores achieved on the intellectual measures for both samples. Verbal type tests show these relationships much more extensively than the performance tests. The findings imply that aged subjects may be more intellectually capable than their test performances suggest and that hearing is an important variable to be considered in the assessment of their cognitive functioning.

Some electronystagmographic manifestations of central nervous system disease.

A battery of tests with electronystagmography were performed on two groups of patients, one in which posterior fossa abnormalities had been confirmed independently by neurologic findings, contrast studies, or surgery; the other group consisted of what seemed clinically clear cut peripheral VIII nerve or labyrinthine disturbances. The two groups were compared statistically for the incidence of factors thought to indicate the presence of brain stem lesions. No single factor is absolutely reliable by itself as an indicator of brain stem disease, but the use of a test battery permits a much more accurate indication of probability of the presence of brain stem lesions.

Vertigo of delayed onset after sudden deafness.

An entity of episodic true vertigo of delayed onset following sudden and profound sensorineural hearing loss is described. Data on 12 patients and three case reports are presented. The latency between sudden deafness and the onset of the vertigo varied from 1 to 68 years. The vestibular symptoms are identical to the vestibular symptoms of Ménière's disease, and there is some evidence that endolymphatic hydrops in the previously deafened ear represents at least part of the labyrinthine pathology. Labyrinthectomy in the deaf ear was curative. Tentatively, this entity is best considered a variant of Ménière's disease.